The tobacco industry has added a wide range of chemicals to cigarettes to increase product stability and modify taste and sensory qualities of smoke. While the Family Smoking Prevention and Tobacco Control Act outlawed tobacco flavor additives, menthol was exempt from regulation. Mentholated cigarettes are especially popular with beginning smokers and in minority populations disproportionally affected by COPD, lung cancer and hypertension. Recently, electronic cigarettes, marketed as non-toxic nicotine delivery devices, have become popular tobacco cigarette substitutes. Electronic cigarettes contain large amounts of the same chemical flavor and sensory additives outlawed for use in tobacco cigarettes, including irritating terpenes such as linalool. Our research has shown that menthol, at levels similar or below in smoke of mentholated cigarettes, strongly inhibited the respiratory irritation response to tobacco smoke irritants in mice. Aerosols from electronic cigarettes elicited strong irritation responses in mice, comparable to responses elicited by tobacco cigarette smoke. Physiological experiments showed that menthol and linalool are potent modulators of TRPM8 and TRPA1, two chemosensory ion channels expressed in sensory neurons innervating the respiratory system. We hypothesize that: 1.) Menthol acts as a counterirritant, blocking sensory neuronal responses to inhaled noxious chemicals through interaction with TRPA1 or TRPM8, 2) As a tobacco additive, menthol facilitates smoke inhalation through inhibition of neuronal irritant receptor signalling, thereby accelerating nicotie dependence and lung disease and , 3) the high amounts of chemical additives in electronic cigarettes are added to mimic the sensory impact of tobacco smoke and may cause chronic irritation and inflammatory responses. The studies proposed in this application will use physiological, biochemical, molecular and behavioral approaches to:
Aim 1.) Define the roles of TRPA1 and TRPM8 in menthol-induced inhibition of acute respiratory irritation.
Aim 2.) Examine the pharmacological effects of menthol and menthol-related compounds on irritant-induced activation of sensory neurons.
Aim 3.) Determine the effects of menthol inhalation on smoking-induced lung inflammation and emphysema.
Aim 4.) Investigate the sensory and inflammatory effects of electronic cigarette aerosols and their chemical additives. Our proposed research will provide new insights into neuronal mechanisms of airway irritation and remodeling, and define a scientific basis for regulatory efforts targeting menthol and other additives to tobacco and electronic cigarettes.

Public Health Relevance

As an additive to cigarettes, menthol is suspected to accelerate and maintain nicotine dependence and to increase the toxicity of tobacco smoke. Electronic cigarettes, rapidly gaining market share as supposedly non-toxic nicotine delivery devices, also contain flavor additives and other chemicals with unknown health effects. Our research aims to reveal how cigarette additives affect the function of the respiratory system and, potentially, promote addiction and lung disease in smokers.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL105635-03
Application #
8580913
Study Section
Lung Injury, Repair, and Remodeling Study Section (LIRR)
Program Officer
Punturieri, Antonello
Project Start
2011-01-01
Project End
2014-12-31
Budget Start
2013-01-01
Budget End
2013-12-31
Support Year
3
Fiscal Year
2013
Total Cost
$385,883
Indirect Cost
$119,774
Name
Yale University
Department
Pharmacology
Type
Schools of Medicine
DUNS #
043207562
City
New Haven
State
CT
Country
United States
Zip Code
06520
Caceres, Ana I; Liu, Boyi; Jabba, Sairam V et al. (2017) Transient Receptor Potential Cation Channel Subfamily M Member 8 channels mediate the anti-inflammatory effects of eucalyptol. Br J Pharmacol 174:867-879
Smith, Gregory J; Cichocki, Joseph A; Doughty, Bennett J et al. (2016) Effects of Acetaminophen on Oxidant and Irritant Respiratory Tract Responses to Environmental Tobacco Smoke in Female Mice. Environ Health Perspect 124:642-50
Miao, Shida; Beach, Evan S; Sommer, Toby J et al. (2016) High-Intensity Sweeteners in Alternative Tobacco Products. Nicotine Tob Res 18:2169-2173
Kaelberer, Melanie Maya; Jordt, Sven-Eric (2016) A Method to Target and Isolate Airway-innervating Sensory Neurons in Mice. J Vis Exp :
Ha, Michael A; Smith, Gregory J; Cichocki, Joseph A et al. (2015) Menthol attenuates respiratory irritation and elevates blood cotinine in cigarette smoke exposed mice. PLoS One 10:e0117128
Liu, Boyi; Fan, Lu; Balakrishna, Shrilatha et al. (2013) TRPM8 is the principal mediator of menthol-induced analgesia of acute and inflammatory pain. Pain 154:2169-77
Willis, Daniel N; Liu, Boyi; Ha, Michael A et al. (2011) Menthol attenuates respiratory irritation responses to multiple cigarette smoke irritants. FASEB J 25:4434-44